This invention pertains to systems of spaced apart walls providing space into which concrete can be poured to form a concrete wall. Such systems are shown and fully described in applicant""s co-pending application Serial #09/040,659, filed Mar. 17, 1998. Briefly those forms include panels held together by H-shaped tracks to assemble walls for the forms. The walls are then held in substantially parallel relationships by some form of tie member engaged between the parallel walls. These ties are frequently associated with the tracks that hold the panels.
Such systems work well for straight walls. At corners, however, there are frequently problems. Corners in this sense are commonly right angle intersections, but may be less or more than a 90 degree intersection. Further, a corner for the purpose of this application may be a rounded corner as well as a sharp angular intersection.
At such corner, it is fairly common for the panels of plastic forming the wall section to be pulled apart, thus separating the panel from the rails. This is particularly true of the outer wall at the corner, though the inner wall, too, may separate.
By this invention, a rail combination forming the corner of the wall is formed with gripping parts which have a strong tendency to hold the panel piece in the rail and therefore to prevent separation at the corners.